Analysis of generic antiretroviral formulations manufactured in India

Highly active antiretroviral therapy has significantly modified the natural history of HIV infection, decreasing mortality and the incidence of opportunistic infections [1]. However, 90% of infected individuals worldwide do not have access to these drugs [2], because their cost is too high for the developing countries that are most affected by the AIDS epidemic. India is a major producer of generic antiretroviral drugs that are widely used in developing countries because they are less expensive than those produced elsewhere. There have, however, been reports of generic medications, including antiretroviral agents, which contain little or no active ingredients [3,4]. It is therefore important that generic antiretroviral medications be analysed for drug content. Data describing the integrity of these drugs are not publicly available except for a report by Penzak et al. [5] on nevirapine. We analysed the content of six commonly used nucleoside and non-nucleoside reverse transcriptase inhibitors alone and in combination, from three Indian sources (Aurobindo Pharma, Ranbaxy and Cipla) and compared the values with proprietary medications manufactured in the United States. The antiretroviral drugs tested were efavirenz (600 mg), nevirapine (200 mg), zidovudine (300 mg), didanosine (250 mg), stavudine (30 mg), lamivudine (150 mg) and a combination pill containing nevirapine, stavudine and lamivudine in the same dosages. They were physician's samples given by the drug companies for patient use during July–August 2003. The date of manufacture of the drugs was from December 2001 and June 2003 and expiration dates were from December 2003 and April 2006. Six tablets/capsules of each drug were processed and analysed in duplicate by high-performance liquid chromatography (HPLC). The entire tablet/contents of the capsule were crushed into a fine powder and dissolved in methanol. Appropriate dilutions of the drug solutions were made in methanol and the methanolic solutions were injected into a Waters HPLC (Milford, MA, USA) with a Waters 300 mm × 3.9 mm micro Bondapak reverse phase C18 column. The syrup solutions containing the antiretroviral drugs were suitably diluted in methanol and injected into the HPLC. The methods used to estimate the drugs in the tablet/capsule/syrup were modified from those reported for estimating drug concentrations in blood [6,7]. All drugs, except efavirenz, were monitored using an ultraviolet detector set at 260 nm using a flow rate of 1.5 ml/min and maintaining the column at room temperature. In the case of efavirenz, the ultraviolet detector was set at 245 nm, the flow rate was adjusted to 2.4 ml/min and the column maintained at 40°C. The mobile phase consisted of a mixture of potassium phosphate solution, acetonitrile and methanol in varying proportions for the different drugs. A range of calibration standards containing known concentrations of the drugs were prepared in methanol and run simultaneously. Calibration standards of zidovudine and didanosine were prepared using pure powder obtained from the Sigma Chemical Company (St Louis, MO, USA). In the case of the others, drugs manufactured in the USA were used. These drugs were obtained from the local pharmacies. The concentration of the active ingredient in each tablet/capsule was calculated from the height of the peak that was obtained on the chromatogram and compared with that obtained for the corresponding standard solutions of known drug concentration. Appropriate dilution factors were employed to calculate the drug content in tablets/capsules/syrup. In all, 12 chromatographic analyses were performed for each individual medication. All drug assays were undertaken after coding them. The mean drug content of all the preparations is given in Table 1. They compared well with the proprietary formulations and the variability (coefficient of variation) ranged from 0.01 to 8.3%. All the formulations werwere within the 5% range of the stated contents compared with the proprietary drugs, except for stavudine and lamivudine, which were slightly higher but within the 10% range.Table 1: Antiretroviral drug content from different sources.This report adds to the published data on the content of antiretroviral drugs manufactured outside the USA. Penzak et al. [5] analysed nevirapine from six international sources representing four countries and three manufacturers, and reported an average nevirapine content of 99% in tested preparations compared with labeled amounts. In the present study, analyses of specific antiretroviral medications supplied by Aurobindo Pharma, Ranbaxy and Cipla from India indicate that the amount of active drug is very similar to those medications manufactured in the USA. Although these data are encouraging given the widespread use of such products in the developing world, further studies are required to evaluate whether these results are applicable consistently to randomly selected lots of the drugs. Studies documenting bioequivalence between generic and proprietary antiretroviral medications and bioavailability in different populations are also necessary. This information will enable healthcare providers and governmental agencies to choose the antiretroviral formulations most likely to provide HIV-infected patients in the developing world with the greatest possibility of clinical benefits. Acknowledgements The authors acknowledge the Fogarty AIDS International Training and Research Program, Lifespan/Tufts/Brown Center for AIDS Research for funding this project. They also thank Aurobindo Pharma, Ranbaxy and Cipla for granting permission to carry out drug analysis of their products. They are grateful to Dr Kenneth Mayer, Program Director, Fogarty AITRP and Dr P.R. Narayanan, Director, Tuberculosis Research Center for their encouragement and support. The secretarial assistance provided by Mr B. Doraiswamy is acknowledged.